去极化电流法对10kV电缆绝缘老化诊断的研究

Diagnosis of 10kV XLPE cables insulation aging condition based on the depolarization current method

为了对10k V运行电缆绝缘状态进行简单、快速评估,提出一种基于去极化电流的诊断方法,对水树老化交联聚乙烯电缆绝缘状态进行评估,并对其诊断参数进行了研究。首先通过水树加速老化装置在电缆样本中生成明显的水树。然后采用虚拟仪器(Labview)配合Keithely皮安表与高压真空开关系统完成去极化电流控制采集平台的搭建。利用搭建的测试平台对不同长度和不同老化时间的电缆样本进行去极化电流测试,通过对去极化电流曲线的积分,提出了基于去极化电流放电量的电缆绝缘老化判别方法。结果表明:长电缆的去极化放电量远大于短电缆,老化电缆的放电量大于新电缆,且老化程度越严重,稳定后去极化电流值越大。说明该去极化电流法能准确有效判别电缆绝缘老化问题。

In order to assess the 10kV power cable insulation condition simply and rapidly , this paper proposed a di-agnosis method based on the depolarization current .Insulation conditions of water tree aged XLPE cable were assessed using this method , and the diagnosis parameters of the method were discussed .Firstly, a water-needle method was employed to obtain water tree aged cables samples .Using the virtual instrument （ Labview ） , Keithely picoammeters and high-voltage vacuum switch system , a current test platform was constructed to collect the depolarization current . Samples of different length were subjected to perform depolarization current measurements , and diagnosis method based on depolarization discharge quantity was put forward by integrating the depolarization current measurement curve .The results show that depolarization discharge quantity of long cable is greater than that of short one , and the depolarization current values of samples tend to increase with aging time .The experiment indicates that depolarization current measurements can effectively assess the insulation condition of power cable .